<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0, user-scalable=no">
    <meta http-equiv="X-UA-Compatible" content="ie=edge,chrome=1">
    <meta name="referrer" content="never">
    <title>设定弹性容器</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        ul {
            list-style: none;
        }

        .box {
            display: flex;
            width: 200px;
            height: 200px;
            background-color: #f00;
        }

        .inner {
            display: flex;
            width: 60px;
            height: 60px;
            background-color: #00f;
        }

        .inner span {
            width: 30px;
            height: 30px;
            background-color: #333;
        }

        span.inner {
            background-color: #0f0;
        }
    </style>
</head>
<body>
    <!-- 
        弹性容器具有块状特征
            - 主轴：默认水平方向，起点在左
            - 交叉轴：默认垂直方向，起点在上

        弹性容器中的直接子元素称为弹性元素
            - 宽高起作用
            - 沿主轴的起点往终点方向排列
            - 变为弹性容器，仍与其它弹性元素排列在一起
    -->
    <div class="box">
        <div class="inner">
            <span></span>
        </div>
        <span class="inner"></span>
    </div>

    <span>hello world</span>

    <script type="text/javascript">
        
    </script>
</body>
</html>